One of the problems with installing exhaust hoods in industrial, commercial, and large residential systems is adjusting the flow rate of each hood so that a minimum volume of air is exhausted to ensure capture, containment, and removal of effluent. The performance of a hood, however, is very variable depending upon how it is installed. Often, unforeseen adjustments made in the size and length of ducting and other variables established during installation make it impossible to select an exhaust blower configuration which will deliver a desired exhaust flow once a hood is installed. Because of the cost of unnecessarily high exhaust capacity, it is important to establish a desired exhaust flow upon installation.
Currently, one way of dealing with this problem is for an installer to perform a flow measurement and make adjustments to a fan system to establish a desired flow. However, such field measurements and procedures are time consuming and subject to error and common sloppiness.